Optimization of Laser Peening Parameters Using Taguchi Method

Abstract:

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Using Taguchi method to optimize the critical parameters of laser peening (LP) is
presented firstly. The objective of the study is to assess the impact of laser parameters on the laser
peen strengthening for the 6061-T6 aluminum alloy and optimize the process parameters to achieve
higher surface residual compressive stress. In order to reduce the process cost and time, the finite
element method was applied to simulate the LP process. The Taguchi method is used to formulate
the experimental layout and establish the order of predominance among the identified critical
parameters, and predict the optimal setting for each process parameter. The results show that three
parameters related to the magnitude of compressive residual stress imply different effects. Laser
shot diameter ranks first, followed by pulse width and laser power in terms of their effects on the
magnitude of compressive residual stress. The best combination of levels is given by the levels (3, 3,
2). The optimal result was confirmed with a superior ultimate surface residual compressive stress of
125MP.

Abstract: The hole cold expansion is a well-known technique used to improve the fatigue life in mechanical structures. An approach named simulation experiment was used to establish the relationships between maximum residual stress and the process parameters in order to quantitatively understand residual stress status around the hole after expansion working. Firstly, Finite Element Method was employed to substitute the physical experiments to get the residual stress distribution of the hole of different expansion ratios, hole diameters and plate heights. Secondly, Excel software was used to obtain the trend curves of maximum residual compressive stress of different parameters. Then the equations of trend curves were obtained based on the least square principle. The results show that the simulation experiment approach is practical to implement and meet the actual accuracy need of engineering, and could establish the foundation for analysis of the fatigue life in mechanical structures.

Abstract: The paper examines the influence of cutting parameters, namely cutting speed and feed rate on the tool life in machining process of cylindrical billets made from a Duplex Stainless Steel (DSS). Two optimization methods is presents, one based on the Taguchi design of the experiment with orthogonal array L9 and signal-to-noise ratio (S/N) and the second based on the dynamic programming approach with modified Dijkstra's algorithm have been used to find optimal levels of the control parameters. ANOVA was performed to determine the significance of the input variables. A predictive mathematical model has been developed through a regression analysis to study the response. The results at optimum cutting conditions are predicted using estimated values. Finally, the features, the merits and the limitations of the presented optimization approaches were discussed.